Gastric Cancer-Induced Neutrophil Extracellular Traps: A Potent Mediator of Cancer Associated Thrombosis
Abstract Background: Development of venous thromboembolism (VTE) is associated with high mortalities among gastric cancer (GC) patients. Neutrophil extracellular traps (NETs) have been reported to correlated to procoagulant and prothrombotic in some diseases. We aimed to clarify that NETs participates in the development of cancer-associated thrombosis in GC.Method: The level of NETs in blood and tissue samples of patients were analyzed by ELISA and flow cytometry. NETs generation in vitro were observed by immunofluorescence (IF). The NETs procoagulant activity (PCA) was performed by fibrin formation and thrombin-antithrombin complex (TAT) assays. Hypercoagulation of platelets and endothelial cells (ECs) stimulated by NETs were measured by IF and flow cytometry. Thrombosis in vivo was measured in an established mice model of VTE induced by flow stenosis in the inferior vena cave (IVC).Result: NETs are likely to form in blood and tissue samples of GC patients compared with healthy individuals. In vitro studies that GC cells and their conditioned medium (CM), but not gastric mucosal epithelial cell can stimulate NETs releasing from neutrophils. In addition, NETs induced hypercoagulation of platelets by up-regulating the expression of phosphatidylserine (PS) and P-selectin on the cells. Furhter, NETs stimulate adhesion of normal platelets on glass surfaces. Similarly, NETs trigger the conversion of ECs to hypercoagulable phenotypes by down-regulating the expression of their intercellular tight junctions but up-regulating that of tissue factor (TF). Treatment of normal platelets or ECs with NETs augmented the level of plasma fibrin generation and TAT complex. Meanwhile, in the models of IVC stenosis, tumor-bearing mice demonstrate stronger ability to form thrombi and NETs were abundantly accumulated in the thrombi compared with control mice. Notably, combination of DNase-1, activated protein C (APC) and Sivelestat markedly abolished the PCA of NETs.Conclusion: Our findings demonstrate that GC-induced NETs strongly increase the risks of VTE development both in vitro and in vivo. Given that inhibitors of NETs disrupt hypercoagulation, NETs are potential therapeutic target against VTE.